Is this a properly formatted nested dictionary, or something else?

Question

I am learning Python, and seem to have become stuck on a problem involving the basics of nested dictionaries.

My code pulls data from an API and I get data aback in the following structure, but I am not sure this is a properly formatted nested dictionary?

I have been trying to understand nested dictionaries, and I thought a nested dictionary had to be along the lines of the following:

people = {1: {'name': 'John', 'age': '27', 'sex': 'Male'},
          2: {'name': 'Marie', 'age': '22', 'sex': 'Female'}}

To me, it seems the data being returned by the API does not use indexes.

"Brands": [
  {
   "brand_id": "brand1",
   "brand_display": "Brand One",
   "brand_is_common": "No",
   "brand_country": "UK"
  },
  {
   "brand_id": "brand2",
   "brand_display": "BRand Two",
   "brand_is_common": "Yes",
   "brand_country": "USA"
  },
  {
   "brand_id": "brand3",
   "brand_display": "Brand Three",
   "brand_is_common": "No",
   "brand_country": "UK"
  },

etc etc

If I want to iterate through the data I get from the API, how would I do that without indexes?

How would I look up data without indexes?

@StephenRauch I do not think it is correct to conflate arrays and `lists`. — gmds, Jun 21 '19 at 05:03
@gmds, conflate? In this context you see an important distinction between a json array and a python list? — Stephen Rauch, Jun 21 '19 at 12:33

score 0 · Answer 1 · answered Jun 21 '19 at 06:19

you can iterate through the results very easily, just check the following example:

api_response = {
  "Brands": [
    {
    "brand_id": "brand1",
    "brand_display": "Brand One",
    "brand_is_common": "No",
    "brand_country": "UK"
    },
    {
    "brand_id": "brand2",
    "brand_display": "BRand Two",
    "brand_is_common": "Yes",
    "brand_country": "USA"
    },
    {
    "brand_id": "brand3",
    "brand_display": "Brand Three",
    "brand_is_common": "No",
    "brand_country": "UK"
    }
  ]
}

for brand in api_response["Brands"]:
  print(brand["brand_id"] + " " + brand["brand_country"])

Output:

brand1 UK
brand2 USA
brand3 UK

score 0 · Accepted Answer · answered Jun 21 '19 at 06:33

First of all, your description and example of a nested dictionary is correct. However, I am not totally clear on what the data you are showing is. In your example output from the api, the code segment ends with a comma, you should edit it so that people can see the whole output with correct formatting. As the example stands currently, it does not have valid syntax in python. If the actual api output is exactly as you've shown it, then it looks like the data is formatted in json and not python. If you want to see how parse json data in python check this answer, Deserialize a json string to an object in python .

I am going to assume that the data you get from the API looks something like this (I removed the comma and added a back brace and enclosed the set with curly braces to make it valid python, I've also assigned it to a variable so we can access it's values by key):

api_output = { 
"Brands": {[
  {
   "brand_id": "brand1",
   "brand_display": "Brand One",
   "brand_is_common": "No",
   "brand_country": "UK"
  },
  {
   "brand_id": "brand2",
   "brand_display": "BRand Two",
   "brand_is_common": "Yes",
   "brand_country": "USA"
  },
  {
   "brand_id": "brand3",
   "brand_display": "Brand Three",
   "brand_is_common": "No",
   "brand_country": "UK"
  }]} 
}

We are looking at an dictionary with the following structure:


example_dict = {
                 "example_key":{ 
                                 [ #the square brackets denote a list
                                  {"sub_key":sub_value,"sub_key0":sub_value0},  
                                  {"sub_key":sub_value} #these dicts are stored in the list
                                 ]
                               }    
                 }

Your intuition was correct, the api is not returning a nested dictionary. The data format seems to be a dictionary with a string key, whose value is a list, which contains a set of dictionaries.

So going back to your example, we need to navigate both a list and a dictionary. To access values in a list we go by index, and to access values in a dictionary we go by key. Since the list of dictionaries is stored as a value of another dictionary we use it's corresponding key to access the list.

list_of_brands = api_output["Brands"] #assign the value of "Brands" to a variable

#we can check the value type (not needed but useful for understanding whats going on)

type(list_of_brands)

#out: list

Now we need to iterate through the list by index to get to the dictionaries it contains, and then assuming want to check every key in every dictionary, we will iterate through the keys of the dictionary and do something with the value:

for brand in list_of_brands: # for each dictionary in the list  
    for key in brand: # loop through the keys of the current dict,
        print(" key: " + key + "\n value: " + brand[key]) #prints the key and its value

To put it all together the code looks like this:

api_output = { 
"Brands": {[
  {
   "brand_id": "brand1",
   "brand_display": "Brand One",
   "brand_is_common": "No",
   "brand_country": "UK"
  },
  {
   "brand_id": "brand2",
   "brand_display": "BRand Two",
   "brand_is_common": "Yes",
   "brand_country": "USA"
  },
  {
   "brand_id": "brand3",
   "brand_display": "Brand Three",
   "brand_is_common": "No",
   "brand_country": "UK"
  }]} 
}

for brand in list_of_brands: # for each dictionary in the list  
    for key in brand: # loop through the keys of the current dict,
        print(" key: " + key + "\n value: " + brand[key]) #prints the key and its value

Hopefully this helped you better understand what is going on!

*THANK YOU* for that detailed and helpful answer! – WannaBeCoder Jun 21 '19 at 14:47 — WannaBeCoder, Jun 21 '19 at 14:47

Is this a properly formatted nested dictionary, or something else?

2 Answers2